Certified Rhythm Analysis Technician (CRAT) Practice Exam

Atrial fibrillation is characterized by chaotic and asynchronous electrical activity in the atria. This condition results in disorganized electrical signals, leading to rapid and irregular heartbeats. Instead of a unified contraction, the atria quiver or fibrillate, which prevents effective blood filling into the ventricles. The presence of these chaotic impulses is a hallmark of atrial fibrillation, causing its characteristic erratic rhythm on an electrocardiogram (ECG).

This contrasts with the other choices. For example, while multiple asynchronous premature atrial contractions might occur before the onset of atrial fibrillation, they do not define it. Retrograde synchronous or asynchronous electrical activities suggest a more organized pattern than what is seen in atrial fibrillation, where the hallmark is disorganization and lack of coordination. Thus, the defining feature of atrial fibrillation is indeed the chaotic, asynchronous electrical activity found in the atrial chambers.